Veniaminof

United States

56.17°N, 159.38°W; summit elev. 2507 m

All times are local (unless otherwise noted)

AVO reported that the ongoing low-level eruption of Veniaminof, characterized by lava effusion and emission of minor amounts of ash and steam, continued during 17-23 July, indicated by nearly continuous volcanic tremor and occasional small explosions detected by the seismic network. On most days satellite images showed elevated surface temperatures at the cinder cone inside the caldera consistent with lava effusion. The web camera in Perryville (32 km SSE) recorded nighttime incandescence and low-level ash-and-steam plumes during 22-23 July. The Volcano Alert Level remained at Watch and the Aviation Color code remained at Orange.

Geologic Background. Massive Veniaminof volcano, one of the highest and largest volcanoes on the Alaska Peninsula, is truncated by a steep-walled, 8 x 11 km, glacier-filled caldera that formed around 3700 years ago. The caldera rim is up to 520 m high on the north, is deeply notched on the west by Cone Glacier, and is covered by an ice sheet on the south. Post-caldera vents are located along a NW-SE zone bisecting the caldera that extends 55 km from near the Bering Sea coast, across the caldera, and down the Pacific flank. Historical eruptions probably all originated from the westernmost and most prominent of two intra-caldera cones, which rises about 300 m above the surrounding icefield. The other cone is larger, and has a summit crater or caldera that may reach 2.5 km in diameter, but is more subdued and barely rises above the glacier surface.